柳枝稷和坚尼草的耐镉性初步研究

为了探究镉污染条件下开发能源植物的可行性,以高生物量黍属能源植物柳枝稷和坚尼草为材料,温室中苗期水培试验,分别对柳枝稷外源施加浓度为0,0.5,5,10,20,50,100μmol/L镉(Cd),对坚尼草施加浓度为0,2,5,7.5,10μmol/L Cd,从形态、生长生理等角度,分析两种能源草对镉的响应。结果表明:随Cd浓度的增加,柳枝稷和坚尼草生物量和根伸长量均下降,Cd浓度为50μmol/L时,柳枝稷根鲜重减少达显著水平(P0.05)。而坚尼草则在Cd浓度为2μmol/L时,根和地上部分总鲜重减少达显著水平。相比于对照,Cd浓度为2μmol/L时,坚尼草的根伸长量已下降96.3%,而柳枝稷在5μmol/L Cd时根伸长量才降低55.0%,柳枝稷的耐镉性高于坚尼草。经20μmol/L镉处理,柳枝稷的地上部镉浓度达40mg/kg,生物量下降了45%。不同浓度的镉处理下,镉在柳枝稷体内的迁移指数为5.9%~14.2%,柳枝稷可以在Cd污染条件下被开发为能源和修复植物种植。此外,实验还发现,在根平均直径为0~1mm范围内,柳枝稷的总根长、根表面积和根体积与镉积累呈显著负相关,与迁移指数呈显著正相关(P0.05),该结果说明,细根在植物的镉吸收积累和转运中可能起着非常重要的作用。

Preliminary research on Cd-tolerance of Panicum virgatum and Panicum maximum

It is important to evaluate the capability of heavy metal tolerance of high biomass grasses for develo-ping bioenergy plants suited to heavily polluted environments,particularly metal pollutants,reducing the prob-lem of bioenergy crops competing with staple food crops.Both switchgrass (Panicum virgatum )and guinea grass (P .maximum)are important bioenergy plants because of their high yield potential.These grasses were used to examine the effects of cadmium (Cd)on seedling growth under 0,0.5,5,10,20,50,100 μmol/L Cd for switchgrass,0,2,5,7.5,10 μmol/L Cd for guinea grass grown using hydroponic techniques.Root and shoot fresh weights of both grasses were recorded and root morphological data of switchgrass were obtained u-sing an EPSON scanner and WinRHIZO software.ICP-AES was used to examine Cd accumulation in switch-grass.The results showed that the biomass and root elongation of switchgrass and guinea grass were signifi-cantly affected by Cd.The root biomass of switchgrass decreased greatly under 50 μmol/L Cd conditions,but root biomass,shoot biomass,total biomass and root elongation in guinea grass were decreased by 86.1%, 83.5%,84.1% and 96.3% respectively by the 2 μmol/L Cd treatment;root elongation in switchgrass was re-duced by 55% in 5 μmol/L Cd solution.The Cd concentration in shoots of switchgrass was 40 mg/kg and the biomass was reduced by 45% in the 20 μmol/L Cd treatment.In addition,the root length and root tip numbers in switchgrass were significantly decreased in Cd treatments in comparison with the control.However,mean root diameter increased in Cd solutions.There was a significant negative correlation between root length,root surface area and root volume,and Cd accumulation and a strong positive correlation between root length,root surface area and root volume and TFs in the 0-1 mm mean root diameter class suggesting that fine roots may play an important role in Cd accumulation.